1. Dynamic Memory Allocation
9.8
Dynamic Memory Allocation

2. Dynamic Memory Allocation
Can allocate storage for a variable while program is running
Computer returns address of newly allocated variable
Uses new operator to allocate memory:
double *dptr = nullptr;
dptr = new double;
new returns address of memory location 2

3. Dynamic Memory Allocation
Can also use new to allocate array: const int SIZE = 25; arrayPtr = new double[SIZE];
Can then use [] or pointer arithmetic to access array:
for(i = 0; i < SIZE; i++)
*arrayptr[i] = i * i; or
*(arrayptr + i) = i * i;
Program will terminate if not enough memory available to allocate 3

4. Releasing Dynamic Memory
Use delete to free dynamic memory:
delete fptr;
Use [] to free dynamic array:
delete [] arrayptr;
Only use delete with dynamic memory! 4

5. Dynamic Memory Allocation in Program 9-14

6. Dynamic Memory Allocation in Program 9-14
Program 9-14 (Continued)

7. Dynamic Memory Allocation in Program 9-14
Program 9-14 (Continued)
Notice that in line 49 nullptr is assigned to the sales pointer. The delete operator is designed to have no effect when used on a null pointer.

8. Returning Pointers from Functions
9.9
Returning Pointers from Functions

9. Returning Pointers from Functions
Pointer can be the return type of a function:
int* newNum();
The function must not return a pointer to a local variable in the function.
A function should only return a pointer:
to data that was passed to the function as an argument, or
to dynamically allocated memory 9

10. From Program 9-15

11. Using Smart Pointers to Avoid Memory Leaks
9.10
Using Smart Pointers to Avoid Memory Leaks

12. Using Smart Pointers to Avoid Memory Leaks
In C++ 11, you can use smart pointers to dynamically allocate memory and not worry about deleting the memory when you are finished using it.
Three types of smart pointer:
Must #include the memory header file:
In this book, we introduce unique_ptr:
unique_ptr
shared_ptr
weak_ptr
#include <memory>
unique_ptr<int> ptr( new int );

13. Using Smart Pointers to Avoid Memory Leaks
The notation <int> indicates that the pointer can point to an int .
The name of the pointer is ptr .
The expression new int allocates a chunk of memory to hold an int.
The address of the chunk of memory will be assigned to ptr.

14. Using Smart Pointers in Program 9-17